Why does HAS recommend a single dose of vaccine for former coronavirus patients?

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How to vaccinate people who have already contracted the disease against the coronavirus? Very recently, the High Authority of Health (HAS) ruled on this issue by publishing its new recommendations on the vaccine.

Just one dose to boost immunity

Most people having already contracted the disease induced by SARS-CoV-2 exhibit natural immunity. On the other hand, it is still poorly understood and gray areas remain such as the level of this immunity depending on the person or its duration. Several studies have concluded that the production of antibodies can generate immunity for up to five to eight months.

In our country, the High Authority of Health (HAS) published new recommendations on February 12, 2021. This is an update from current knowledge on immunity to the virus. Following the advice of the French-speaking infectious pathology society (SPILF), the HAS recommends vaccination in a three to six months after recovery patients. In addition, she recommends the administration of a single dose of vaccine for these former patients.

However, it should be remembered that the vaccines from Pfizer, AstraZeneca and even Moderna were originally necessarily involve two injections at a very precise interval. The first injection effectively gives the start of immunity, but the second is responsible for actually registering the latter in time. It is therefore quite normal that the recommendation to administer a single dose may come as a surprise. In fact, the HAS estimates that people already infected for the first time have a certain immune memory and that only one injection of vaccine would thus act as a reminder.

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Preserve vaccine stocks

In fact, a person who contracted the virus between three and six months ago could therefore be vaccinated. However, she would receive only one dose, the objective of which would be to boost immunity and to re-register it in time. A second dose would then be considered superfluous. This recommendation also aims to preserve stocks and optimize the vaccination campaign.

In contrast, cured people with immunosuppression will need two doses. These people who do not (or little) produce antibodies must therefore follow the same pattern as people who have never contracted the disease. In addition, the HAS added another recommendation. If a person who received the first injection of the vaccine contracted the disease soon after, the second injection should not be done. Again the principle of three to six months after healing will apply.

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